Salt Damaged Lawn

Q: I am a realtor in Indiana and have searched the web for this problem with no success. My clients did a walk through the day before closing on their new condo and noticed a huge spot of dead grass. When we asked the former owners at the closing they said the lawn maintenance people had put too much fertilizer on that spot. Not true! The new owners moved in the next day and the neighbors told them the former owner’s movers dumped the salt out of the water softener onto the lawn. This condo was built just two years ago and sod was put down at that time. I don’t think the lawn people will take care of the problem since they didn’t cause it. My question ǃ